Multiscale, three-dimensional characterization of shock absorption in lightweight fibre reinforced cementitious systems

保护系统的发展不仅依赖于超强的力量，还依赖于消散能量和吸收冲击的机制的组合。众所周知，战略包裹体，如轻质固体和离散增强材料，会在局部失效，并在此过程中限制结构破坏。不幸的是，由于它们的异质性和组成性质的多样性，评估这些系统中的能量分散的测试仍然主要是宏观的，并且组分尺度之间的内在脱节限制了材料建模。拟议的研究计划将开发一个多尺度模型来预测轻质纤维增强水泥基复合材料中的负荷率效应，并具体完成：i)对此类系统中的能量耗散机制进行二维和三维量化；ii)在微观、细观和宏观尺度上对其回弹描述符进行实验评估；iii)对此类高性能系统中的高应变率敏感性进行预测性本构建模。 这项建议将整合我们对胶凝材料中动态裂纹扩展和止裂过程的理解，这些材料在标准测试下已证明具有高性能重量比。断裂试验和无损技术的结合将被用来量化水泥基复合材料对动态载荷的体积响应。这一结果有望对非均质脆性基质系统的速率敏感性提供一般的信息，并产生具有多尺度耗能的减震系统。 4名研究生研究助理(1名博士和3名硕士)和5名本科生将加入研究团队。他们将与盟国地区的研究人员互动。通过一组不同的学生研究人员的参与，将向新一代高素质人员介绍高应变率测试、无损技术、计算模拟和高性能结构材料的使用。

The development of protective systems depends not so much on superior strength alone, but on a combination of mechanisms which dissipate energy and absorb shock. Strategic inclusions such as lightweight solids and discrete reinforcement are known to fail locally and in the process, limit structural damage. Unfortunately, due to their heterogeneous nature and diversity in constituent properties, the tests that evaluate energy dispersion in these systems remain mostly macroscopic and the inherent disconnect between component scale has limited material modeling. The proposed research program will develop a multi-scale model to predict load rate effects in lightweight, fibre reinforced cementitious composites and specifically accomplish: i) 2-D and 3-D quantification of energy dissipating mechanisms in such systems; ii) experimental evaluation of their resilience descriptors at micro, meso and macro-scale; iii) predictive constitutive modeling of high strain rate sensitivity in such high performing systems. This proposal will integrate our understanding of dynamic crack growth and arrest process in cementitious materials that have proven high performance-to-weight ratio under standard tests. A combination of fracture tests and non-destructive techniques will be employed to quantify the volumetric response of cementitious composites to dynamic loading. The outcome is expected to inform on the rate sensitivity of heterogeneous brittle matrix systems in general and produce shock absorbing systems with multi-scale energy dissipation. Four graduate research assistants (1 PhD and 3 MSc) and 5 undergraduate students will join the research team. They will interact with research personnel in allied areas. Through the involvement of a diverse set of student researchers, a new generation of high quality personnel will be introduced to the use of high strain rate testing, non-destructive techniques, computational simulations and high performance structural materials.